<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8"/>
        <title></title>
    </head>
    <body>
        <script type="text/javascript">
            var arr4 =  [[1,2,3],[4,5,6],[7,8,9],[0,1,2]];
            for(var i=0;i<arr4.length;i++){
                for(var j=0;j<arr4[i].length;j++){
                    console.log(arr4[i][j]);
                }
                console.log("--------------------")
            }
            
</script>
    </body>
</html>